Advanced magnetic resonance imaging (“MRI”) techniques such as dynamic susceptibility contrast (“DSC”) imaging and dynamic contrast enhanced (“DCE”) imaging have shown promise as noninvasive methods for assessing tumor physiology, which was previously only available through surgical biopsies. DSC-MRI provides several perfusion-based parameters, such as cerebral blood volume (“CBV”), cerebral blood flow (“CBF”), and mean transit time (“MTT”), to represent hemodynamics and vascularity of the imaged tissues. This information is thought to correlate with tumor aggressiveness based on the importance of vascular proliferation in malignancy. In particular, relative CBV—a ratio of tumor CBV to normal white matter CBV—has shown diagnostic reliability in glioma grading. Despite its proven utility, DSC-MRI is subject to susceptibility artifacts because it measures T2 or T*2 changes, making it difficult to assess tumors in close proximity to bone or large vessels. Also, DSC-MRI calculations assume an intact blood-brain barrier, which is often not the case in aggressive tumors.
DCE-MRI provides permeability based parameters such as the volume transfer constant, Ktrans, and plasma volume, Vp, to describe neovascularity and angiogensis in the imaged tissues. Recent work has supported the ability of DCE-MRI parameters, particularly Ktrans, in differentiating high grade and low grade gliomas. Other studies have indicated that DCE-MRI may be valuable in detecting anti-angiogenic treatment response and differentiating radiation injury from tumor recurrence. Furthermore, being a T1-weighted gradient-recalled echo (“GRE”) technique, DCE-MRI has several advantages over DSC-MRI, such as insensitivity to susceptibility artifacts, higher spatial resolution, and improved signal-to-noise ratio (“SNR”).
Recent studies have suggested that the clinical utility of DSC-MRI and DCE-MRI in tumor diagnosis and prognosis is increased when perfusion and permeability parameters are considered in combination. However, DSC-MRI and DCE-MRI scans are typically performed as separate procedures, each with its own contrast injection. Due to logistical, financial, and patient safety concerns related to contrast exposure, physicians are often unable to perform both types of scans for a given patient.
Because DSC-MRI and DCE-MRI parameters are derived from two separate phases of the same process (i.e., contrast evolution through tissue), we propose a novel, combinatorial technique to collect both DSC-MRI and DCE-MRI data in a single scan session using a single contrast injection. The method monitors the acquisition of the DSC-MRI data collection and automatically detects when the first pass of the contrast agent is completed. It then switches to the DCE-MRI data collection without any user intervention.